WSERIAL900 platform - initial contribution

The wserial900 platform is based on A.N. Solutions @ANY900 (Atmel RF212 + Atmel ATmega1281,
http://www.an-solutions.de/products/900_mhz.html) and external EUI chip (Microchip 25AA02E48),
flash (Atmel AT45DB041D) and 2 serial ports (ST3232). Optimized to DIN rail case.
Flash on module @ANY900 (Atmel AT25F2048) is not used because it is connected Rx/Tx serial pins.